Radiotherapy systems, methods and software

ABSTRACT

A photon therapy delivery system can deliver radiation therapy to a patient via a photon beam. The system can utilize a controller configured to facilitate delivery of radiation therapy via a photon beam and also a particle beam. This can include receiving radiation therapy beam information for radiation therapy treatment of a patient utilizing the particle beam and photon beam. Also, patient magnetic resonance imaging (MRI) data can be received during the radiation therapy treatment. Utilizing the patient MRI data, real-time calculations of a location of dose deposition for the particle beam and for the photon beam can be determined taking into account interaction properties of soft tissues through which the particle beam passes.

RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. ProvisionalApplication No. 62/595,478, filed Dec. 6, 2017, which is herebyincorporated by reference in its entirety.

BACKGROUND

Radiotherapy uses beams of radiation to kill cells to treat disease,typically proliferative tissue disorders such as cancer. Radiotherapycan be used to treat targets in patients requiring a dose of ionizingradiation for curative effect, such as grossly observable tumors,anatomic regions containing microscopic disease or potential diseasespread, or regions that include margins for motion and/or deliveryuncertainties. The ionizing radiation delivered by radiotherapy beamsdestroys the DNA and other important components of diseased cells andprevents the cells from replicating.

Typical radiotherapy involves treatment planning to determine how todeliver the prescribed radiation dose to the target, while at the sametime sparing healthy tissues in the vicinity by limiting doses belowacceptable thresholds to prevent deadly or debilitating side effects.

SUMMARY

Radiation therapy systems (e.g., photon therapy delivery systems) aredisclosed for delivery of radiation therapy to a patient (e.g., via aphoton beam). Certain embodiments may include a controller configured tofacilitate delivery of radiation therapy via a photon beam and also aparticle beam.

The delivery of radiation therapy with the photon beam and the deliveryof radiation therapy via a particle beam can both be completed withouthaving to move the patient. The photon therapy delivery system can beconfigured to deliver radiation therapy to a patient via photon beamsfrom multiple directions. Also, the system can include a magneticresonance imaging system (MRI) configured to acquire images of thepatient during administration of radiation therapy.

Also disclosed are computer program products that allow the receiving ofradiation therapy beam information for a radiation therapy treatment ofa patient utilizing a particle beam and a photon beam. Patient magneticresonance imaging (MRI) data can be received during the radiationtherapy treatment. Further, the patient MRI data can be utilized toperform real-time calculations of a location of dose deposition for theparticle beam and for the photon beam, taking into account interactionproperties of soft tissues through which the particle beam passes.

In certain embodiments, the influence of a magnetic field produced by anMRI system on the particle beam and on the photon beam can also be takeninto account in performing the real-time calculations of location ofdose deposition. The patient MRI data and the radiation therapy beaminformation can be utilized to calculate accumulated dose deposition tothe patient during the radiation therapy treatment. Optionally, theradiation therapy treatment can be re-optimized based on the calculateddose deposition.

Also disclosed is another computer program product that enables thereceiving of patient radiation therapy prescription information and thereceiving of patient magnetic resonance imaging (MRI) data. A radiationtherapy treatment plan can be determined that includes combining photonbeam delivery and particle beam delivery. The determining of theradiation therapy treatment plan can utilize the patient radiationtherapy prescription information and the MRI data.

Implementations of the current subject matter can include, but are notlimited to, methods consistent with the descriptions provided herein aswell as articles that comprise a tangibly embodied machine-readablemedium operable to cause one or more machines (e.g., computers, etc.) toresult in operations implementing one or more of the described features.Similarly, computer systems are also contemplated that may include oneor more processors and one or more memories coupled to the one or moreprocessors. A memory, which can include a computer-readable storagemedium, may include, encode, store, or the like, one or more programsthat cause one or more processors to perform one or more of theoperations described herein. Computer implemented methods consistentwith one or more implementations of the current subject matter can beimplemented by one or more data processors residing in a singlecomputing system or across multiple computing systems. Such multiplecomputing systems can be connected and can exchange data and/or commandsor other instructions or the like via one or more connections, includingbut not limited to a connection over a network (e.g., the internet, awireless wide area network, a local area network, a wide area network, awired network, or the like), via a direct connection between one or moreof the multiple computing systems, etc.

The details of one or more variations of the subject matter describedherein are set forth in the accompanying drawings and the descriptionbelow. Other features and advantages of the subject matter describedherein will be apparent from the description and drawings, and from theclaims. While certain features of the currently disclosed subject matterare described for illustrative purposes in relation to particularimplementations, it should be readily understood that such features arenot intended to be limiting. The claims that follow this disclosure areintended to define the scope of the protected subject matter.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, show certain aspects of the subject matterdisclosed herein and, together with the description, help explain someof the principles associated with the disclosed implementations. In thedrawings,

FIG. 1 is a graph showing the penetrative depth of various exemplaryforms of radiation therapy into human tissue;

FIG. 2 is a flowchart for a method of radiation therapy treatmentplanning for particle radiation therapy, utilizing MRI data, that can beimplemented by software;

FIG. 3 is an illustration of a radiation therapy system having one ormore features consistent with the present description;

FIG. 4 is an illustration of a radiation therapy system having one ormore features consistent with the present description;

FIGS. 5A-5B illustrate a shielding system for shielding, for example, aportion of a dosimetry system of a particle therapy system, having oneor more features consistent with the current description;

FIG. 6 is a flowchart for a method of particle radiation therapytreatment having one or more elements consistent with the presentdescription;

FIG. 7 is an illustration of a combined radiation therapy system havingone or more features consistent with the present description;

FIG. 8 is an illustration of a combined radiation therapy system havingone or more features consistent with the present description; and

FIG. 9 is an illustration of a combined radiation therapy system havingone or more features consistent with the present description.

DETAILED DESCRIPTION

Systems, methods and computer software are disclosed herein for theperformance of radiotherapy that may utilize therapy provided by bothphoton beams (e.g., x-rays) and also by particle beams. Such may beutilized, as described herein, in combination with magnetic resonanceimaging.

The disclosure below first introduces specific concepts relating toparticle therapy, treatment planning for particle therapy, and particletherapy utilizing magnetic resonance imaging. Following such aredescriptions of therapy that can combine particle therapy with photonbeam therapy. It is contemplated and understood that the majority ofconcepts relating to particle therapy described our similarly applicableto the combination of particle therapy with photon beam therapy.

Particle therapy is a form of radiotherapy using beams of energeticparticles for the treatment of disease, for example, cancer. Particlebeams can be aimed at a target within a patient and can cause damage tothe DNA and other important cellular components of the target cells,eventually causing the death of the cells. Cancerous cells have lessability than non-cancerous cells to repair radiation damage and aretherefore particularly susceptible to particle therapy. Depending on thecontext, “particle therapy” is sometimes used to refer to therapy withhadrons, such as protons, neutrons, antiprotons, mesons, etc., while itmay also refer to therapy utilizing ions or nuclei, such as lithiumions, helium ions, carbon ions, etc. Often, therapy with ions such ascarbon ions is said to be “heavy ion therapy,” although the line between“light ions” and “heavy ions” is not precisely defined. As used herein,the terms particle therapy, particle radiation therapy, particle beamand the like, refer to therapy utilizing hadrons as well as nuclei (orions). This terminology specifically excludes therapies such as photontherapy or electron-beam therapy.

FIG. 1 is a graph 100 showing the penetrative depth of various forms ofradiation therapy into human tissue. For a given energy, electron beamshave a low penetrative depth into human tissue (as shown by trace 102)compared to other radiation therapy forms. X-ray beams penetrate humantissue to a greater depth than electrons, but the dose absorbed bytissue falls off with the penetrative depth of the X-rays as shown bytrace 104. Particle therapy beams deposit more of their energy at aparticular depth into the tissue of the patient at the end of theirrange, as shown by trace 108. This depth near the end of their range maybe referred to as the Bragg Peak, shown as 108. A benefit provided byparticle therapy is that less energy is deposited into healthy tissueoutside of the target, thereby reducing the potential for damage to thehealthy tissue. Additionally, beyond the Bragg peak there is very littledose deposited compared to X-Ray beams.

Before particle radiation therapy can take place, a treatment plan mustbe generated. The present disclosure contemplates the optional use ofmagnetic resonance imaging (MRI) data in a particular fashion ingenerating a treatment plan, which will have a predicted dose depositionclosely matching the actual dose delivered to the patient and closelymatching the desired dose. X-ray computed tomography (CT) imaging datamay also be employed to determine, for example, the mass density of thepatient's tissues and regions of the patient that contain low and highdensity tissues or regions such as lung, air, and bone. The analysis canbe performed for all particle beam paths.

A magnetic resonance imaging system can be employed to obtain MRI datathat, when analyzed, can more accurately determine the types of softtissues along beam paths to and through the target. Particle interactionproperties can then be determined from the MRI data, allowing for a moreaccurate determination of the dose delivered to the patient's tissuesand to the target. In addition, the MRI data can enable more accuratedetermination of the biological effectiveness of the particle beamtherapy.

The present disclosure contemplates that the MRI data may be combinedwith X-Ray CT data (for example, by using deformable image registration)to improve the accuracy of chemical composition and mass densitydetermination and thus improve the determination of particle therapydoses. If X-Ray CT data is not available, regions containing bone may bedetermined by ultra-short echo time (TE) MR imaging, while lung and airmay be determined from proton density weighted MR imaging.

X-Ray CT is well suited to produce a map of electron densities in thehuman body and is useful in determining dose delivered by photon beamradiation therapy because photons' dominant interaction probabilitiesare proportional to electron density. Electron densities are also wellcorrelated to mass density due to the fact that, for human tissues, theatomic numbers are low where nuclei have a fairly constant ratio ofneutrons to protons. CT Hounsfield numbers reflect the attenuationcoefficient of human tissues to X-rays. Thus, the Hounsfield number maybe identical for a variety of combinations of elemental compositions,elemental weights and mass densities, not to mention that the measuredHounsfield number may be inaccurate due to image beam hardening effectsand other artifacts. The uncertainty of elemental composition introducedwhen defining tissues using X-Ray CTs and Hounsfield numbers can causethe determined range of a particle beam to err significantly. This errorcan lead directly to dose computation errors, for example, becauseparticle stopping powers are required to accurately model dosedeposition along an energetic particle's path and to determine where theparticles reach the end of their range. Uncertainties in stopping powerdirectly translate into uncertainties in the location of the Bragg peak108, as illustrated in FIG. 1, which can move large dose regions off oftargets and tumors, failing to deliver an effective dose to thetreatment target and, instead, delivering particle radiation therapydose to healthy tissues that should be shielded from receiving highdoses of particle radiation.

Soft tissues have better contrast and definition when imaged with MRIsystems over X-Ray CT. As noted, X-Ray CT is excellent at determiningthe mass density of tissues with very different densities and thedefinition of regions containing air or cortical bone, due to its low orhigh contrast and low or high Hounsfield numbers. But, many soft tissueswill have very similar densities, with very different elementalcompositions. For example, tissues can have a fat-like (or adipose-like)nature or a water-like (or muscle-like) nature while having a verysimilar mass density, and hence such are hard to distinguish with X-RayCT data. Image noise, artifacts, and low contrast in X-Ray CT dataconspire to often misidentify tissue types with current methods. Interms of stopping powers, removing any density dependence, thedifference in stopping power between fat-like tissue (CH2) or water-liketissue (OH2) is dominated by the difference in atomic number between Oand C. For energies above tens of MeV/nucleon, as used in particletherapy, the ratio of stopping powers is significant.

Acquiring MRI data with pulse sequences that are sensitive to only wateror only fat, allows for the water-to-fat ratio of tissues to bedetermined through, for example, Dixon methods or sandwich echoes. Thedetermined water-to-fat ratios in the vicinity of the treatment targetcan then be employed to improve the knowledge of the elementalcompositions of the soft tissues. An MRI can obtain different“contrasts” by reading the signal of the excited protons at differenttimes and/or in different ways (the signal decays differently dependingon what type of molecule the hydrogen is attached to). It is thereforepossible to better differentiate different tissue types and deducechemical compositions utilizing an MRI.

The interactions (frequency and type of interaction) of a particle beamwith the tissues it is passing through depends on a number of factorsincluding beam particle type, particle energy, and the mass density andchemical composition of the tissue. Particle interactions, at least forcharged particles, include Coulomb interactions (i.e., electromagneticinteractions). Coulomb interactions almost always lead to a small energyloss of the incident particle and/or a small deflection in direction.Deflections, which cause the beam to spread out, are referred to asCoulombic scattering. The amount of energy lost per unit length may bereferred to as stopping power. The small energy losses that particlesexperience in Coulomb interactions are due to ionizations andexcitations of the atoms and molecules of the tissue. The frequency ofsuch interactions determines the ionization density along the path of aparticle. The higher the ionization density, the higher the probabilityfor cell damage. This is often measured with a quantity termed linearenergy transfer (LET).

Particle interactions also include nuclear interactions, which are lessfrequent than Coulomb interactions but are much more catastrophic. Theytend to result in the nucleus having been hit disintegrating intofragments (e.g., individual protons and neutrons, deuterons, tritons,lithiums, alphas, etc.). The type and number of such fragments depend onthe incident particle type and energy, and the nucleus that has beenhit. Nuclear interactions also leave behind radioactive nuclei, whichdecay and deposit additional dose.

Nuclear interactions and Coulombic scattering are highly dependent onatomic numbers of the nuclei. They both lead to broadening of a Braggpeak. For ions, nuclear interactions are also responsible for the tailof dose deposited beyond the Bragg peak. When there are heterogeneitiesin the beam path (e.g., air cavities, bones), Coulombic scattering leadsto a complex dose deposition structure behind the heterogeneity.

When the term interaction properties is utilized herein, it refers toany combination of interaction properties such as the Coulombicinteractions and nuclear interactions described above. Preferredembodiments of the present disclosure for, e.g., treatment planning orreal-time MRI guidance of radiation therapy, will utilize as manyinteraction properties as necessary in determining the location andquantity of dose deposition in patient tissues.

“Heavy ions” such as Carbon ions tend to have a much more devastatingeffect on cells than protons. Their nuclear interaction fragments havehigh LETs and tend to deposit their energy locally around theinteraction site. This is the main mechanism responsible for Carbon ionshaving a much higher “biological effectiveness” than protons. This leadsto both more cells being killed (or damaged) per unit energy depositedin the tissue for ions compared to photons, electrons and even protons.The energy deposited in tissue is referred to as absorbed dose, measuredin Gray (Gy). One Gy of absorbed dose from a Carbon ion beam will kill3-12 times more cells than one Gy of absorbed dose from a photon orelectron-beam, due to the differences in biological effectiveness.

With particle beam therapy, determination of the biologicaleffectiveness is beneficial or even required for proper treatment. Thereare a number of different ways to determine biological effectiveness.For example, the determination of a biologically effective dose (BED)aims to indicate quantitatively the biological effect of a particularradiotherapy treatment, taking into account numerous factors such as thetype of therapy, dose per fraction, dose rate, etc. In addition,relative biological effectiveness (RBE) is a ratio comparing theabsorbed dose for a particular mode of therapy to an absorbed dose forphoton therapy, where each dose leads to the same biological effect.

For protons, it has been assumed for years that RBE is constant ataround 1.1, but some have opined that this leads to suboptimal planningresults. Because the RBE for protons is so close to 1.0, neglecting toperform such a biological effectiveness calculation may not have toosignificant an effect on therapy but for neutrons, ions, mesons, etc.,RBE is much higher and can have a very significant effect on therapy ifnot taken into account.

To determine biological effectiveness, one needs to know the energyspectrum of the incident beam as well as the interaction properties ofthe materials or tissues that the beam passes through. Thus, preciseknowledge of the chemical composition of the tissues is absolutelyessential for accurate determinations of biological effectiveness. It isalso important to determine where the incident particle beam has lostthe majority of its energy (i.e., the Bragg peak). In addition,contributions to the dose distribution due to nuclear reactions,activation of tissues, time dose fractionation and cell damage vs.recovery can be incorporated into determination of biologicaleffectiveness. For these reasons, patient MRI data is important in thedetermination of biological effectiveness measures, similar to itsimportance in dose calculation and treatment planning.

MRI data can similarly be employed to allow evaluation of tissueelemental composition and accurate dose computation for the evaluationof the quality of a delivery plan before delivery. If the quality of thedose to be delivered is insufficient, the data collected at setup can beemployed to re-optimize a particle therapy treatment plan beforedelivery. This can be performed immediately prior to delivery of thetherapy, while the patient is on the treatment couch, or prior to thepatient's arrival for the actual treatment.

FIG. 2 is a flowchart for a method 200 of radiation therapy treatmentplanning for particle radiation therapy, utilizing MRI data, that can beimplemented by software, the method having one or more featuresconsistent with the present description. The software can be implementedusing one or more data processors that may be part of a systemcontroller. The software can include machine-readable instructions,which, when executed by the one or more data processors, can cause theone or more data processors to perform one or more operations.

In FIG. 2, at 202, patient radiation therapy prescription informationcan be received. Patient radiation therapy prescription information mayinclude data such as minimum dose required to a target tumor, maximumdose allowed to nearby organs of interest, or the like. The patientradiation therapy prescription information described herein is notintended to be limiting. The patient radiation therapy prescriptioninformation received at the radiation therapy treatment planning systemcan include prescription information typical for radiation therapytreatment planning.

At 204, patient MRI data can be received. In some variations, thepatient MRI data can be received from a magnetic resonance imagingdevice integrated with a particle therapy system. Patient MRI data mayencompass the region of interest for treatment, including, for example,a target treatment area of the patient and surrounding tissue thatradiation therapy beams may pass through and for which radiation doseshould be monitored. The MRI data may be taken before treatment at adifferent location from the treatment itself, or the MRI data may beacquired on the treatment table where an MRI is integrated with theparticle radiation therapy system.

At 206, a radiation therapy treatment plan can be determined for usewith a particle beam. The radiation therapy treatment plan can utilizethe patient radiation therapy prescription information and utilize thepatient MRI data to account for interaction properties of soft tissuesin the patient through which the particle beam passes. The radiationtherapy treatment plan can include, for example, the number of beams tobe utilized, the direction from which the beam(s) will be delivered, theenergy of the beam(s), collimator configurations, and the like.

Determination of the radiation therapy treatment plan can also accountfor the influence of the magnetic field of an MRI on the particle beam.This involves including the influence of the strong magnetic field ofthe MRI on transport of the ionizing radiation depositing dose in thepatient. The interaction cross sections are not strongly influenced bypolarization of spins as they compete with thermal effects (e.g., atbody temperatures only about four parts per million of spins are alignedwithin a 1 Tesla magnetic field), but the magnetic field exerts anexternal Lorentz force on moving charged particles that can be accountedfor to produce a more accurate dose computation.

Determination of the radiation therapy treatment plan can also includedetermination of a biological effectiveness of the dose delivered to thesoft tissues of the patient by the particle beam, through utilization ofthe patient magnetic resonance imaging data.

FIG. 3 is an illustration of a particle therapy system 300 having one ormore features consistent with the present description. To energizeparticles, the particles are first accelerated by a particle accelerator302. The particle accelerator can be a synchrotron, cyclotron, linearaccelerator, or the like. A synchrotron may be fed by either alow-energy cyclotron or a low-energy linear accelerator. The energy ofthe particle beam 304, prior to any downstream adjustment, determinesthe penetrative depth of the energized particles into the patient 306.Particle accelerators typically produce an energized particle beamhaving a defined energy. In some variations, the energy of the particlescan be reduced, for example, by running the beam through an attenuatingmedium. It is preferable for such to be done away from the patient dueto secondary neutrons that can increase unnecessary dose to the patient.The attenuating medium may be a wedge of material on a wheel or lineardrive that can be rotated to increase or decrease the energy. Themaximum energy is obtained by not applying any attenuating material inthe beam. The minimum is obtained by applying the thickest amount ofattenuating material in the beam. For a known material, a thickness canbe determined that would halt all energized particles from reaching thepatient to stop or interrupt the beam without deactivating the system.

Synchrotrons may also be configured to control beam energy by increasingor decreasing the number of passes through the accelerating elements inthe synchrotron ring. In principle, a linear accelerator can also changethe number of accelerating units, to a few fixed energies, over alimited range. Pulse to pulse energy changes are possible with theproper equipment.

In some variations, a particle therapy gantry 312 can be used to directthe energized particle beam 304 to the patient 306. The patient 306 canbe positioned on a couch 314 within the center of the particle therapygantry 312. The particle therapy gantry 312 can include gantryelectro-magnets 316 configured to direct the beam toward the patient306, through a dosimetry system 318.

The particle therapy gantry 312 can be configured to rotate tofacilitate delivery of particle therapy at different angles. In somevariations, the particle therapy gantry 312 can be configured to rotate360 degrees. One or more slip rings can be employed to facilitate thedelivery of electrical power to the electro-magnets other componentsdisposed on the particle therapy gantry 312. In some variations, theparticle therapy gantry 312 can be configured to rotate with a field ofrotation of approximately 360 degrees. In such variations, the particletherapy gantry 312 may rotate in one direction as far as it will go andthen rotate back in the other direction as far as it will go. Rotatingthe particle therapy gantry 312 around the patient 306 can facilitatedelivery of the energized particle beam 304 to the target at differentangles improving the sparing of healthy tissue and treatment planquality.

The particle therapy gantry 312 may include scanning beam magnets 320.The scanning beam magnets 320 can include, for example, pairs ofelectro-magnets. The pairs of electro-magnets can be arranged to havetheir magnetic fields in orthogonal planes to one another. The scanningbeam magnets 320 can be configured to manipulate the direction of theenergized particle beam 304. In some variations, scanning beam magnets320 can be configured to direct the energized particle beam in ascanning motion back and forth across the treatment target of thepatient.

In some variations, the system can include a fixed beamline 322. Thefixed beamline 322 can be configured to deliver the energized particlesdirectly to a patient through a dosimetry system 318, without a gantry.The system may also include one or more scanning beam electro-magnets320 configured to modify the direction of the energized particles of thefixed-line beam.

The particle therapy system may also include a scatterer. The scatterercan be configured to cause the energized particle beam 304 to scatteroutward. The system can also contain a beam wobbler or raster scanningmechanism to spread out the beam. The system can also include acollimator. The collimator can be a multi-leaf collimator comprising aplurality of thin metallic blades. The thin metallic blades can bemoveable, the position of which can be controlled by a computer. Thethin metallic blades can be configured to absorb the energeticparticles. The thin metallic blades can be arranged, by a controller,such that the shape of an aperture they form is complementary to thetarget within the patient. In this manner, the collimator can facilitateshielding of healthy tissue surrounding the target while permitting theenergized particles to penetrate to the target. In some variations, acollimator carved into a permanent shape may be used. Similarly, a boluscan be positioned in the path of the energized particle beam 304, whichmay be formed from a material semi-permeable to the energized particles,and may be carved to compliment the shape of the tumor.

FIG. 4 is an illustration of a particle therapy delivery system 400having one or more features consistent with the present disclosure. Theparticle therapy delivery system 400 can have one or more elementssimilar to the elements of the system 300, illustrated in FIG. 3. Theparticle therapy system 400, according to the present disclosure, mayinclude a particle therapy delivery system for delivery of radiationtherapy to a patient via a particle beam, a magnetic resonance imagingsystem 402 configured to obtain patient magnetic resonance imaging (MRI)data during radiation therapy; and, a controller 424 configured toreceive patient MRI data during radiation therapy and utilize thepatient MRI data to perform real-time calculations of the location ofdose deposition for the particle beam(s), taking into accountinteraction properties of the soft tissues in the patient through whichthe particle beam passes.

The particle therapy delivery system 400 may include a split magnet MRI402. The split magnet MRI 402 can include two split main magnets 404 and406. The radiation therapy system can include an isocenter 407. The twosplit main magnets 404 and 406 can be separated by a plurality ofbuttresses 408. The plurality of buttresses 408 can be located nofurther from the isocenter 407 than the outer boundary of the two splitmain magnets 404 and 406. While the two split main magnets 404 and 406are each referred to as a single magnet, this terminology is notintended to be limiting. The two split main magnets 404 and 406 can eachinclude a plurality of magnets for the purpose of obtaining MRI data ofthe patient.

A split MRI system is illustrated in FIG. 4 for illustrative purposesonly. The MRI system used can be any type of MRI system. For example,the main magnets can include vertical open magnets, short bore magnets,magnets with a portal or thin section, or the like.

A couch 410 can be disposed within the split MRI system 402. The splitMRI system 402 can be configured to receive a patient 412, on the couch410, through the internal apertures of the two split main magnets 404and 406.

The split magnet MRI system 402, couch 410 and patient 412 can all bedisposed within a particle therapy gantry, such as gantry 312illustrated in FIG. 3. The particle therapy gantry may be configured torotate about the patient 412 delivering particle therapy to the patientfrom a multitude of angles.

The plurality of buttresses 408 can be disposed between the two main MRImagnets 404 and 406 and positioned within the outer periphery of the twomain MRI magnets 404 and 406 so as not to further increase the overalldiameter of the MRI system. The system may include, as an example, threebuttresses 408 spaced at equal angles around the two main MRI magnets404 and 406. The system can be operated such that the particle beam isdirected toward the patient between the split magnets and in a mannersuch that it will not travel through any of the buttresses 408.

The particle therapy system can be configured to facilitate delivery ofenergized particles to the patient such that the energized particles aredirected into a gap 419 between the two main MRI magnets 404 and 406.

Particle therapy delivery system 400 can include a dosimetry system 416for monitoring the radiation therapy to the patient. The dosimetrysystem 416 can also include one or more components to facilitate thedelivery of particle therapy to the patient, for example, by providingfeedback to a controller.

The particle therapy delivery system 400 can include one or moreshielding structures 420 that may, for example, surround at least aportion of the dosimetry system. Shielding structures 420 can beconfigured to house electronic equipment that would otherwise beadversely affected by radiofrequency interference or by the magneticfields produced by main MRI magnets 404 and 406.

FIGS. 5A-5B illustrate an exemplary shielding structure 500 forshielding at least a portion of a dosimetry system 502 of a particletherapy delivery system, having one or more features consistent with thepresent disclosure. The shielding structure 500 may comprise a pluralityof shells. The plurality of shells can be formed from a series ofconcentric shields configured to shield magnetic fields produced by thesplit magnet MRI system 402 illustrated in FIG. 4. The concentricshields may be configured to surround at least a portion of a dosimetrysystem 502. The present disclosure further contemplates shieldingstructures that may include one or more layers of RF absorbing materialsor RF reflecting materials, or combinations of both to, for example,minimize potentially adverse effects of RF radiation emanating from alinear accelerator utilized in certain aspects of the disclosure.

The shielding structure 500 can include a first shield container 504.The first shield container 504 can comprise a cylindrical body portion506 and an annular disk 508 disposed across one end of the cylindricalbody portion. The annular disk 508 can include an aperture 510 to allowthe particle particles to pass through unhindered. In some variations,the first shield container 504 can have a diameter of approximatelyseventeen inches. The diameter of the first shield container 504 can beselected to sufficiently house at least a portion of the components ofthe dosimetry system 502.

The shielding structure 500 can comprise a plurality of shells. Forexample 504, 512 and 514 in FIG. 5B, or the like. The plurality ofshells 504, 512, 514 can be nested together. At least one of theplurality of shells preferably includes an annular disk 516, 518, or thelike.

The shielding structure 500 may be positioned in a fixed location withrespect to split magnet MRI system 402, or may be configured to rotatewith a gantry, such as gantry 312 illustrated in FIG. 3. One or morestructures can be disposed opposite or around the split magnet MRIsystem 402 and configured to mimic the magnetic properties of shieldingstructure 500 in order to minimize interference with the homogeneity ofthe MRI's magnetic fields.

FIG. 6 is a flowchart for a method 600 of radiation therapy treatmentfor particle radiation therapy, utilizing MRI data, that may beimplemented by software, the method having one or more featuresconsistent with the present description. The software can be implementedusing one or more data processors. The software can includemachine-readable instructions, which, when executed by the one or moredata processors, can cause the one or more data processors to performone or more operations. Method 600 is an example of the operations thatcan be performed by controller 424, as discussed herein.

At 602, radiation therapy beam information for radiation therapytreatment of a patient utilizing a particle beam can be received. Theradiation therapy beam information can include one or morecharacteristics of a particle beam. The one or more characteristics caninclude an indication of penetrative abilities of the particle beam, thespread characteristics of the particle beam, the number of particlebeams, or the like.

At 604, patient magnetic resonance imaging (MRI) data can be receivedduring the radiation therapy treatment.

At 606, the patient MRI data can be utilized to perform real-timecalculations of a location of dose deposition for the particle beam,taking into account interaction properties of soft tissues in thepatient through which the particle beam passes, as discussed herein. Theinfluence of a magnetic field produced by an MRI system on the particlebeam may also be accounted for in performing the real-time calculationsof location of dose deposition, as discussed above. And, a determinationof the biological effectiveness of dose delivered to the soft tissues bythe particle beam, through utilization of the patient magnetic resonanceimaging data, may also be performed in conjunction with the real-timedose calculations.

At 608, the particle beam can be interrupted if real-time calculationsof the location of dose deposition indicate that deposition is occurringoff-target.

In some variations, the energy of the particle beam can be adjusted ifthe real-time calculations of the location of dose deposition indicatethat deposition is occurring off-target. In other variations, thepatient MRI data can be utilized and the real-time calculations of thelocation of dose deposition to modify a direction of the particle beamin order to track a target.

As further detailed herein, concepts described with regard to theexemplary method for radiation therapy of FIG. 6 may also be utilized insystems, methods and computer software combining particle therapy withphoton therapy.

In certain implementations of the present disclosure, a particle therapydelivery system may be combined with a photon therapy delivery systemand the system controller can be configured to facilitate the deliveryof both particle beams and photon beams. For example, particle therapy(such as proton therapy) may be delivered in combination with therapyfrom a linear accelerator configured to deliver an x-ray beam. Thecombined system may be configured such that the particle therapy andphoton therapy are delivered alternatively during a treatment session,but without requiring movement of the patient between therapy types. Thepatient is preferably located on a couch with respect to an isocentershared by both the particle therapy system and the photon therapy system(although small patient movements are contemplated within the spirit ofthe disclosure).

In a combined particle/photon therapy system, the particle therapysystem may be configured to have a single fixed beam line, multiplefixed beam lines, or a gantry system, and the photon therapy system maybe configured to deliver photon beams from a multitude of angles (e.g.,via a rotating gantry, a robotic arm, or the like).

Preferred embodiments of the present disclosure do away with the needfor a particle therapy gantry system, instead delivering particletherapy from one or a small number of fixed beam lines and supplementingsuch therapy with photon beam therapy that can be delivered from agreater number of angles. Such combined therapy systems can result inhigher quality treatment plans that, for example, can improve thesparing of healthy tissue surrounding a treatment target.

FIG. 7 illustrates an exemplary radiation therapy system combiningaspects of a photon therapy delivery system 702 and a particle therapydelivery system 704 (only portions of which are depicted in the figure).Photon therapy system 702 in the FIG. 7 example is a linear acceleratorconfigured to produce x-ray beams, however, the present disclosurecontemplates alternative photon therapy systems including radioisotopes,etc. Electron-beam systems may also be utilized.

FIG. 7 depicts one particular implementation of photon therapy deliverysystem 702 where portions of a linear accelerator are disposed around agantry 706. Such portions may be separated to different positions ongantry 706 and may be connected to one another utilizing RF waveguides708. The present disclosure further contemplates that one or moreportions of the photon therapy system may be contained within shieldingstructures 710 that may take forms similar to the shielding structuresdiscussed above with regard to FIG. 5.

Gantry 706 may also include an additional empty shielding structure 712configured to shield at least a portion of the dosimetry system 416 ofthe particle therapy system 704. Such an empty shielding structure 712can similarly take the form of any of the shielding structures discussedabove with regard to FIG. 5. Although the embodiment depicted in FIG. 7shows an empty shielding structure 712 mounted on the gantry, is alsocontemplated that the particle therapy dosimetry system's shieldingstructure may be mounted independent of the gantry, for example, mounteddirectly to the floor, adjacent photon therapy system 702 and its gantry706.

In operation, photon therapy delivery system 702 is configured todeliver a photon beam 714 from various angles toward a patient, and thecombined radiation system can be utilized to deliver particle therapy inthe exemplary manner partially depicted in FIGS. 8 and 9. In thisexemplary manner of operation, gantry 706 can be rotated so that emptyshielding structure 712 is aligned with a particle therapy beam line716, as shown in FIG. 8. Following such, a beam line extender 718 can beutilized to extend the particle therapy system's dosimetry system 416 toa location at least partially within empty shielding structure 712, asdepicted in FIG. 9. A telescoping vacuum chamber is one example of abeam line extender although other methods for changing the position ofthe particle therapy system's dosimetry elements are contemplated.

As noted above, the present disclosure also contemplates embodimentswhere the particle dosimetry system's shielding structures are locatedoff of the gantry. In such embodiments, a beam line extender may not berequired. In addition, an empty shielding structure may not be requiredon gantry 706 and instead gantry 706 may simply be rotated to a positionthat will ensure minimal interference with the particle therapy beam bythe photon therapy system equipment.

In some implementations of the present disclosure, certain particletherapy delivery system components may be beneficially located away fromthe photon therapy delivery system. In one example, particle therapysystem deflection/bending magnets may be located away from the photontherapy system or even outside of the patient therapy vault. Fringeshielding may be employed to isolate such components 720 from photontherapy delivery system 702 and may include, for example, RF shielding722 and/or magnetic shielding 724. Such fringe shielding may also beemployed to isolate such components 720 from a magnetic resonanceimaging system that may be utilized with the combined photon/particletherapy system.

The combined photon and particle therapy systems of the presentdisclosure may be utilized with a magnetic resonance imaging system, aspreviously described above with regard to particle therapy. For example,the magnetic resonance imaging system 402 depicted in FIG. 4 may beemployed in conjunction with a combined particle/photon system, anexample of which is depicted in FIG. 7. In such an example, the photontherapy system 702 and its gantry 706 may be disposed within the gap 419of FIG. 4's magnetic resonance imaging system 402.

As discussed above with respect to particle therapy, integration ofmagnetic resonance imaging with a combined particle/photon therapysystem similarly results in the realization of a number of benefits.This disclosure contemplates each of the applicable benefits discussedabove being realized with the combined particle/photon system including,but not limited to, the ability of the system to receive patientmagnetic resonance imaging (MRI) data during treatment and to utilizesuch data to perform real-time calculations of the location of dosedeposition for a particle beam and also for a photon beam. In addition,the system's controller can be configured to interrupt the particle beamand/or the photon beam if the real-time calculations of the location ofdose deposition indicate that dose deposition is occurring off-target.Also, the system may be configured to calculate accumulated dosedeposition to the patient during a radiation therapy treatment and tore-optimize treatment based on the calculated dose deposition.

The present disclosure contemplates that the calculations disclosed inthe embodiments herein may be performed in a number of ways, applyingthe same concepts taught herein, and that such calculations areequivalent to the embodiments disclosed.

One or more aspects or features of the subject matter described hereincan be realized in digital electronic circuitry, integrated circuitry,specially designed application specific integrated circuits (ASICs),field programmable gate arrays (FPGAs) computer hardware, firmware,software, and/or combinations thereof. These various aspects or featurescan include implementation in one or more computer programs that areexecutable and/or interpretable on a programmable system including atleast one programmable processor, which can be special or generalpurpose, coupled to receive data and instructions from, and to transmitdata and instructions to, a storage system, at least one input device,and at least one output device. The programmable system or computingsystem may include clients and servers. A client and server aregenerally remote from each other and typically interact through acommunication network. The relationship of client and server arises byvirtue of computer programs running on the respective computers andhaving a client-server relationship to each other.

These computer programs, which can also be referred to programs,software, software applications, applications, components, or code,include machine instructions for a programmable processor, and can beimplemented in a high-level procedural language, an object-orientedprogramming language, a functional programming language, a logicalprogramming language, and/or in assembly/machine language. As usedherein, the term “machine-readable medium” (or “computer readablemedium”) refers to any computer program product, apparatus and/ordevice, such as for example magnetic discs, optical disks, memory, andProgrammable Logic Devices (PLDs), used to provide machine instructionsand/or data to a programmable processor, including a machine-readablemedium that receives machine instructions as a machine-readable signal.The term “machine-readable signal” (or “computer readable signal”)refers to any signal used to provide machine instructions and/or data toa programmable processor. The machine-readable medium can store suchmachine instructions non-transitorily, such as for example as would anon-transient solid-state memory or a magnetic hard drive or anyequivalent storage medium. The machine-readable medium can alternativelyor additionally store such machine instructions in a transient manner,such as for example as would a processor cache or other random accessmemory associated with one or more physical processor cores.

To provide for interaction with a user, one or more aspects or featuresof the subject matter described herein can be implemented on a computerhaving a display device, such as for example a cathode ray tube (CRT) ora liquid crystal display (LCD) or a light emitting diode (LED) monitorfor displaying information to the user and a keyboard and a pointingdevice, such as for example a mouse or a trackball, by which the usermay provide input to the computer. Other kinds of devices can be used toprovide for interaction with a user as well. For example, feedbackprovided to the user can be any form of sensory feedback, such as forexample visual feedback, auditory feedback, or tactile feedback; andinput from the user may be received in any form, including, but notlimited to, acoustic, speech, or tactile input. Other possible inputdevices include, but are not limited to, touch screens or othertouch-sensitive devices such as single or multi-point resistive orcapacitive trackpads, voice recognition hardware and software, opticalscanners, optical pointers, digital image capture devices and associatedinterpretation software, and the like.

In the descriptions above and in the claims, phrases such as “at leastone of” or “one or more of” may occur followed by a conjunctive list ofelements or features. The term “and/or” may also occur in a list of twoor more elements or features. Unless otherwise implicitly or explicitlycontradicted by the context in which it used, such a phrase is intendedto mean any of the listed elements or features individually or any ofthe recited elements or features in combination with any of the otherrecited elements or features. For example, the phrases “at least one ofA and B;” “one or more of A and B;” and “A and/or B” are each intendedto mean “A alone, B alone, or A and B together.” A similarinterpretation is also intended for lists including three or more items.For example, the phrases “at least one of A, B, and C;” “one or more ofA, B, and C;” and “A, B, and/or C” are each intended to mean “A alone, Balone, C alone, A and B together, A and C together, B and C together, orA and B and C together.” Use of the term “based on,” above and in theclaims is intended to mean, “based at least in part on,” such that anunrecited feature or element is also permissible.

The subject matter described herein can be embodied in systems,apparatus, methods, computer programs and/or articles depending on thedesired configuration. Any methods or the logic flows depicted in theaccompanying figures and/or described herein do not necessarily requirethe particular order shown, or sequential order, to achieve desirableresults. The implementations set forth in the foregoing description donot represent all implementations consistent with the subject matterdescribed herein. Instead, they are merely some examples consistent withaspects related to the described subject matter. Although a fewvariations have been described in detail above, other modifications oradditions are possible. In particular, further features and/orvariations can be provided in addition to those set forth herein. Theimplementations described above can be directed to various combinationsand subcombinations of the disclosed features and/or combinations andsubcombinations of further features noted above. Furthermore, abovedescribed advantages are not intended to limit the application of anyissued claims to processes and structures accomplishing any or all ofthe advantages.

Additionally, section headings shall not limit or characterize theinvention(s) set out in any claims that may issue from this disclosure.Further, the description of a technology in the “Background” is not tobe construed as an admission that technology is prior art to anyinvention(s) in this disclosure. Neither is the “Summary” to beconsidered as a characterization of the invention(s) set forth in issuedclaims. Furthermore, any reference to this disclosure in general or useof the word “invention” in the singular is not intended to imply anylimitation on the scope of the claims set forth below. Multipleinventions may be set forth according to the limitations of the multipleclaims issuing from this disclosure, and such claims accordingly definethe invention(s), and their equivalents, that are protected thereby.

What is claimed is:
 1. A radiation therapy system comprising: a photontherapy delivery system for delivery of radiation therapy to a patientvia a photon beam; and a controller configured to facilitate delivery ofradiation therapy via a photon beam and also a particle beam.
 2. Theradiation therapy system of claim 1 wherein the delivery of radiationtherapy via a photon beam and the delivery of radiation therapy via aparticle beam can both be completed without having to move the patient.3. The radiation therapy system of claim 1 wherein the photon therapydelivery system is a linear accelerator and the photon beam is an x-raybeam.
 4. The radiation therapy system of claim 1 wherein the photontherapy delivery system is configured to deliver radiation therapy to apatient via photon beams from multiple directions.
 5. The radiationtherapy system of claim 4 wherein the photon therapy delivery system isat least partially mounted on a gantry.
 6. The radiation therapy systemof claim 5 wherein at least a portion of the photon therapy deliverysystem is contained within a shielding structure.
 7. The radiationtherapy system of claim 6 further comprising a shielding structureconfigured to shield at least a portion of a particle therapy dosimetrysystem.
 8. The radiation therapy system of claim 7 wherein the shieldingstructure configured to shield at least a portion of a particle therapydosimetry system is mounted on the gantry.
 9. The radiation therapysystem of claim 8 further comprising a beamline extender configured tofacilitate repositioning of a particle therapy dosimetry system for thedelivery of therapy from a position at least partially within theshielding structure configured to shield at least a portion of theparticle therapy dosimetry system.
 10. The radiation therapy system ofclaim 9, further comprising a particle therapy delivery system.
 11. Theradiation therapy system of claim 10, wherein the particle therapydelivery system is a proton therapy system and the particle beam is aproton beam.
 12. The radiation therapy system of claim 10, furthercomprising fringe field shielding.
 13. The radiation therapy system ofclaim 1, further comprising: a magnetic resonance imaging system (MRI)configured to acquire images of the patient during administration ofradiation therapy.
 14. A non-transitory computer program product storinginstructions that, when executed by at least one programmable processorforming part of at least one computing system, cause the at least oneprogrammable processor to perform operations comprising: receivingradiation therapy beam information for a radiation therapy treatment ofa patient utilizing a particle beam and a photon beam; receiving patientmagnetic resonance imaging (MRI) data during the radiation therapytreatment; and, utilizing the patient MRI data to perform real-timecalculations of a location of dose deposition for the particle beam andfor the photon beam, taking into account interaction properties of softtissues through which the particle beam passes.
 15. The computer programproduct of claim 14 further comprising taking into account influence ofa magnetic field produced by an MRI system on the particle beam and onthe photon beam in performing the real-time calculations of location ofdose deposition.
 16. The computer program product of claim 14 furthercomprising: interrupting the particle beam or the photon beam if thereal-time calculations of the location of dose deposition indicate thatdose deposition is occurring off-target.
 17. The computer programproduct of claim 14 further comprising: utilizing the patient MRI dataand the radiation therapy beam information to calculate accumulated dosedeposition to the patient during the radiation therapy treatment. 18.The computer program product of claim 17 further comprising:re-optimizing the radiation therapy treatment based on the calculateddose deposition.
 19. A non-transitory computer program product storinginstructions that, when executed by at least one programmable processorforming part of at least one computing system, cause the at least oneprogrammable processor to perform operations comprising: receivingpatient radiation therapy prescription information; receiving patientmagnetic resonance imaging (MRI) data; and, determining a radiationtherapy treatment plan combining photon beam delivery and particle beamdelivery, the determining of the radiation therapy treatment planutilizing the patient radiation therapy prescription information and theMRI data.